One document matched: draft-nomad-mobileip-filters-05.txt

Differences from draft-nomad-mobileip-filters-04.txt



   MIP4 Working Group                           (editor) N. A. Fikouras 
   INTERNET DRAFT                                            A. Udugama 
                                                         K. Kuladinithi 
                                                               C. Goerg 
                                              ComNets-ikom, Uni. Bremen 
                                                               W.Zirwas 
                                                             Siemens AG 
                                                           October 2003 
                                      
                                      
                Filters for Mobile IPv4 Bindings (NOMADv4) 
                    draft-nomad-mobileip-filters-05.txt 
    
    
   Status of this Memo 
    
   This document is an Internet-Draft and is in full conformance 
   with all provisions of Section 10 of RFC2026. 
    
    
   Internet-Drafts are working documents of the Internet Engineering 
   Task Force (IETF), its areas, and its working groups.  Note that      
   other groups may also distribute working documents as Internet-
   Drafts. 
    
   Internet-Drafts are draft documents valid for a maximum of six 
   months and may be updated, replaced, or obsoleted by other documents 
   at any time.  It is inappropriate to use Internet-Drafts as 
   reference material or to cite them other than as "work in progress." 
    
   The list of current Internet-Drafts can be accessed at 
        http://www.ietf.org/ietf/1id-abstracts.txt 
   The list of Internet-Draft Shadow Directories can be accessed at 
        http://www.ietf.org/shadow.html. 
    
    
   Abstract 
    
   Filters for Mobile IPv4 bindings enables mobile nodes to associate 
   one or more Filters with mobility bindings during registration. 
   Flows that match a Filter will be processed as defined by the 
   Filter. In this manner, it is possible for a mobile node to 
   distribute flows or packets of a flow among its available points of 
   attachment, or to request that such flows are dropped before 
   reaching the mobile node. 
    
    
    
    
    
    
    
    
    
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Table of Contents 
 
   1 Introduction.....................................................4 
   2 Terminology......................................................4 
   3 NOMADv4 Protocol Overview........................................6 
 3.1 Protocol Description............................................6 
 3.2 Model of Operation..............................................8 
   4 Backwards compatibility with RFC3344............................10 
 5 Support for Multihoming..........................................10 
   6 Associating Filters with Mobility Bindings......................11 
 6.1 Mobile Node Considerations.....................................11 
  Filters for Mobile IPv4 Bindings Registration Flag................11 
  Creating a new mobility binding with Filters......................12 
  Replacing a Filter of a mobility binding by Index.................12 
  Adding new Filters to an existing mobility binding................12 
  Sharing a Filter between mobility binding.........................12 
  Renewing a mobility binding with Filters..........................12 
  Deleting one or more Filters of a mobility binding................13 
  Deleting all Filters for a mobility binding.......................13 
  Transferring a Filter between mobility bindings...................13 
  The Weight field of the Filter Control Extension..................13 
 6.2 Filtering Agent Considerations.................................13 
  Determining the validity of a Filter Body.........................13 
  Processing Filtering Requests.....................................13 
  Filtering Request contains a Filter declaration with a new Index..14 
  Filtering Request containing Filter declarations with allocated Index
   ..................................................................14 
  Filtering Request containing only Filter Control Extension........14 
  Filtering Request containing only Filter Deletion Extension.......14 
  Filtering Request without any Filter declarations or Extensions...15 
  Applying Filters..................................................15 
 6.3 Home Agent Considerations......................................15 
  Filters for Mobile IPv4 Bindings Flag.............................16 
   7 NOMADv4 Extensions to RFC3344 Registration Messages.............16 
 7.1 Behavior Aggregate Filters (BAF) Extension.....................17 
 7.2 Protocol Extension.............................................18 
 7.3 Source Address Extension.......................................18 
 7.4 Source Network Extension.......................................19 
 7.5 Source Port Extension..........................................20 
 7.6 Source Port Range Extension....................................20 
 7.7 Destination Port Extension.....................................21 
 7.8 Destination Port Range Extension...............................21 
 7.9 Free-Form Extension............................................22 
 7.10 Filter Control Extension......................................23 
 7.11 Filter Deletion Extension.....................................23 
 7.12 Filter Reply Extension........................................23 
  Code Values for Filter Reply Extension............................24 
     
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   8. Security Considerations........................................24 
   9 Intellectual Property Considerations............................24 
   References........................................................25 
   A. Changes from Previous Versions.................................25 
 A.1. Updates from version 02.......................................25 
 A.2. Updates from version 03.......................................26 
 A.3. Updates from version 04.......................................26 
   Authors' Addresses................................................27 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
     
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1 Introduction 
    
   This document extends the Mobile IPv4 [1] protocol by providing the 
   means for mobile nodes to notify Filtering Agents (Mobile IPv4 
   entities that can maintain simultaneous bindings with Filters) of an 
   association between Filters and specific mobility bindings. As such, 
   traffic intercepted by a Filtering Agent will be filtered and 
   individual flows will be handled as indicated by the control 
   information of the Filter. In the most typical scenario, individual 
   flows will be redirected to the (co-located) care-of address 
   indicated by the respective binding. This enables mobile nodes to 
   distribute active flows among their available points of attachment. 
   Alternatively, the mobile node may request when registering bindings 
   and filters that it does not wish to receive certain flows (it 
   wishes to have them dropped, without notification to their source). 
    
   Home Agents are unable to distinguish between individual flows and 
   therefore redirect all intercepted traffic for a mobile node to the 
   (co-located) care-of address indicated by its binding. Consequently, 
   as the binding is updated with every hand-off, the total of a mobile 
   node's active flows are redirected to the most recently registered 
   (co-located) care-of address. Furthermore, if a mobile node requests 
   for simultaneous bindings, it will receive at each registered (co-
   located) care-of address a duplicate copy of every active flow. 
   However, a mobile node that maintains multiple points of attachment 
   may wish to associate certain flows with specific access interfaces. 
   As these access interfaces vary their (co-located) care-of address a 
   mobile node should be able to perform a Mobile IPv4 (IP-layer) hand-
   off for only a subset of its active flows. In addition, a mobile 
   node that has exhausted the bandwidth of a point of attachment 
   should be able to expand a flow across multiple points of attachment 
   to take advantage of the resources available in these networks. 
    
   Filters for bindings require that a mobile node includes in its 
   registration requests or binding updates a list of Filters. In this 
   manner, Filtering Agents (Home or Hierarchy Agents) become aware of 
   the relationship between certain flows and specific bindings. 
   However, the existence of those Filters does not affect in any way 
   the mobile node's choice on the point of attachment to be utilized 
   for the return path. 
    
    
2 Terminology 
    
   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 
   "SHOULD", "SHOULD NOT", "RECOMMENDED",  "MAY", and "OPTIONAL" in 
   this document are to be interpreted as described in RFC-2119 [2]. 
    
   This document uses the following terms: 
    
   Domain   A collection of networks sharing a common network  
            administration. 
    
   Home domain 
     
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            As defined in [5]. 
    
   Visited domain 
            The domain where the mobile node has one or more points of 
            attachment. 
    
   Home Agent (HA) 
            As defined in [1]. 
    
   Correspondent Node (CN) 
            As defined in [1]. 
    
   Gateway Foreign Agent (GFA) 
            As defined in [5]. 
    
   Regional Foreign Agent (RFA) 
            As defined in [5]. 
    
   Home Network 
            As defined in [1]. 
    
   Mobile Node (MN) 
            As defined in [1]. 
    
   Mobility Binding 
            As defined in [1]. 
    
   Filtering Agent (FLA) 
            Mobile IPv4 entities that can maintain Filters for mobility  
            bindings such as the HA, RFA, and GFA. 
    
   Filter Module (FLM) 
            The smallest module from which complex Filters are  
            defined. 
    
   Filter Body (FB) 
            A collection of Filter Modules in a Filter. 
    
   Filter (FL) 
            A collection of a Filter Body and control information  
            describing how a flow(s) should be handled. 
    
   Filtering Request (FLRQ) 
            Mobile IPv4 signaling (registration request, binding  
            update) with the purpose of establishing a new mobility  
            binding that may contain one or more Filters. 
    
   Filtering Reply (FLRP) 
            Mobile IPv4 signaling (registration reply, binding  
            acknowledgment) for returning the result of a Filtering  
            Request. 
    
   Default Filter (DF) 
            A special Filter applicable for all flows not matching any  
     
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            other Filter. Is either defined by mobile node or  
            automatically allocated from Filtering Agents to the  
            lowest defined Index of zero. 
    
   Idle Mobility Binding (IMB) 
            A mobility binding without Filters. 
    
    
3 NOMADv4 Protocol Overview 
    
   This section provides an overview of how Filters for Mobile IPv4 
   bindings can be realized. 
    
3.1 Protocol Description 
    
   Mobile nodes that wish to associate Filters with a (co-located) 
   care-of address are required to issue a registration request or 
   binding update with the æNÆ bit set that may contain a list of 
   Filters that indicate which flows are associated with the registered 
   (co-located) care-of address. Such signaling is termed as Filtering 
   Requests. 
    
   A Filter is consisted of one or more Filter Modules (Filter Body) 
   and is terminated by a Filter Control Extension. A Filter Module may 
   contain several predicates. There is an OR relationship between 
   predicates of a Filter Module. There is an AND relationship between 
   Filter Modules of the same Filter. In order for a flow to match a 
   Filter, it is required to qualify for all of the Filter Modules 
   contained in the Filter. 
    
   Filter management is performed with the help of the Filter Control 
   Extension. It contains a FilterÆs Index and a Weight field. The 
   Index identifies uniquely a Filter for a given mobile node while the 
   Weight field indicates the relative amount of traffic for which a 
   Filter is applicable. If the Weight field is set to zero then all 
   matching flows will be dropped without notification to their source. 
   For any other value of Weight, matching flows will get forwarded to 
   the point of attachment indicated by the corresponding mobility 
   binding. In the case of shared Filters, packets of matching flows 
   will get distributed between multiple points of attachment with 
   respect to the Weight value of each Filter. A mobile node may share 
   a Filter between mobility bindings by issuing a Filtering Request 
   from each respective point of attachment. The first one will contain 
   the full Filter (Filter Body + Filter Control Extension) while all 
   subsequent Filtering Requests will contain only a Filter Control 
   Extension indicating the Index number of the Filter to be shared. 
    
   If a mobile node needs to delete a Filter, then it is required to 
   issue a Filtering Request with a Filter Deletion Extension. The 
   Filter Deletion Extension contains a list of Filter indexes that the 
   mobile node wants to have deleted. 
    
     
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   A mobile node may define more than one Filter for a specific 
   mobility binding. The declaration of these Filters may take place 
   during one or more Filtering Requests. 
    
   Filtering Requests is processed by Filtering Agents. A Filtering 
   Agent can be any Mobile IPv4 entity that can maintain mobility 
   bindings with Filters, like a HA, RFA, GFA or a CN when routing 
   optimization is supported. 
    
   Flows that fail to match any of the defined Filters are handled as 
   defined by the Filter with the lowest possible Index of zero, termed 
   as Default Filter. A mobile node may define some of the attributes 
   of the Default Filter such as the associated mobility binding and 
   its Weight field by issuing a Filtering Request. Otherwise, these 
   will be configured by each Filtering Agent. In that case, the 
   Default Filter is associated with the mobility binding with the 
   longest outstanding lifetime and the Weight will be set to the value 
   of 1. However, different Filtering Agents may use different 
   algorithms to determine the Default Filter. 
    
   A mobile node may issue Filters corresponding to flows that do not 
   yet exist. When such a flow is initiated it will be handled by the 
   Filtering Agents as indicated by the respective Filter. 
    
   A Filtering Agent that receives a Filtering Request is required to 
   establish a mobility binding and set up a tunnel as per [1]. Newly 
   declared Filters should be associated with the registered mobility 
   binding. 
    
   A Filter remains valid for the lifetime of the corresponding 
   mobility binding. If the lifetime of a binding expires then all 
   associated Filters are deleted from record. 
    
   Binding management is performed with the help of the æSÆ bit as 
   described in [1]. Filtering Agents that receive a Filtering Request 
   with the æSÆ bit set are required to establish a new mobility 
   binding while maintain all existing ones. Incoming flows should not 
   get duplicated as defined in [1] rather than filtered and where 
   necessary forwarded to the appropriate point of attachment. 
   Filtering Agents that receive a Filtering Request without the æSÆ 
   bit are required to delete any existing mobility bindings and the 
   associated Filters. When renewing a mobility binding a mobile node 
   must issue a Filtering Request that is not required to contain any 
   reference to any Filters. If a mobile node wishes to reuse a deleted 
   Filter then it will have to reissue a Filtering Request. 
    
   A Filtering Reply is a registration reply containing a Filter Reply 
   Extension for each of the Filters contained in the corresponding 
   Filtering Request indicating the Index of a Filter along with a Code 
   signifying the result. The Code is used to relay success or the 
   reason of rejection to the mobile node. 
    
   Successive updates to the Filters of a mobility binding may lead to 
   a mobility binding without any Filters. Such bindings remain idle 
     
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   until either allocated a Filter, expire or deregistered by the 
   mobile node. A mobility binding in that state is termed as an Idle 
   Mobility Binding. When a Filtering Agent maintains exclusively Idle 
   Mobility Bindings for a mobile node then it is required to act as 
   per [1] and to ignore the behavior presented in this document. 
    
   The rules by which a mobile node decides on the set of Filters are 
   considered beyond the scope of this document. The extensions 
   presented in this document do not affect in any way the mobile 
   nodeÆs choice on the point of attachment to be used when returning 
   traffic. 
    
3.2 Model of Operation 
    
   Filters for Mobile IPv4 Bindings has two modes of operation that can 
   be seamlessly combined but for the sake of simplicity are covered in 
   this section separately. The first model of operation concerns the 
   management of whole flows while the second model addresses the 
   distribution the individual packets of flows between points of 
   attachment. 
    
   Figure 1 illustrates the first model of operation. It shows a mobile 
   node with two home addresses each originating from a different home 
   network (multihoming). The mobile node maintains multiple points of 
   attachment in several visited domains. A visited domain may consist 
   of several different IP administrative domains (subnetworks). The 
   extensions presented do not provide any restriction as to how many 
   points of attachment a mobile node may maintain within a visited 
   domain as long as each point of attachment belongs to a different 
   subnetwork. When a mobile node acquires point of attachment in the 
   home network then it is required to give up all other points of 
   attachment. 
    
   In figure 1, the mobile node has two separate points of attachment 
   in the Mobile IPv4 hierarchy of visited domain A. In addition, the 
   mobile node maintains two more points of attachment through visited 
   domains B and C. The mobile node maintains five incoming flows from 
   correspondent nodes CN1, CN2 and CN3. Flows associated with CN1 are 
   denoted with 'a' and 'b' while the respective flows for CN2 are 
   denoted with 'c' and 'd'. The flow associated with CN3 is denoted 
   with 'e'. 
    
   Communications originating CN1 are addressed to the mobile nodeÆs 
   home address from home network 1. For that home address the mobile 
   node maintains two simultaneous mobility bindings at the GFA each 
   associated with a Filter indicating that flows 'a' and 'b' should be 
   delivered to different points of attachment. 
    
   Flows denoted with 'c', 'd' and 'e' are addressed to the mobile 
   nodeÆs home address from home network 2. These are filtered at HA2 
   and tunneled to different visited domains. The mobile node has 
   indicated in its Filters that it does not wish to receive flow 'e'. 
   As such, flow 'e' is terminated at the HA2 as this the first 
   Filtering Agent encountered in the path to the mobile node and there 
     
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   is no need for that traffic to propagate further into the network. 
   The rejection of a flow will take place either without any 
   notification to its source. 
    
   To return traffic a mobile node may choose any of the available 
   points of attachment. 
    
              +---------------------+   +-------------+     +-------+   
              |  Visited Domain  A  |   |             |     |  CN1  |   
              |                     |   |             |     +-------+   
              |                     |   |             |         a|      
     a a a a a a +------+ a a a     |   |             |         b|      
      -----------|  FA  |-----      |   |             |   +-----a|----+ 
    a|        |  +------+     |a        |             |   |     b|    | 
     |        |           +-------+     |             |   |  +------+ | 
    a|        |           |  GFA  |--------------------------| HA1  | | 
     |        |           +-------+ babababababababababababab+------+ | 
    a|        |  +------+     |b    |   |             |   |           | 
     |   --------|  FA  |-----      |   |             |   |   Home    | 
    a|  |b b b b +------+b b b b    |   |             |   | Network 1 | 
     |  |     |                     |   |             |   +-----------+ 
    a|  |b    +---------------------+   |   Public    |                 
   +------+                             |   Network   |   +-----------+ 
   |  MN  |   +---------------------+   |             |   |   Home    | 
   +------+   |  Visited Domain  B  |   |             |   | Network 2 | 
     |d |c    |                     |   |             |   |           | 
     |  |  c c c +------+ c c c c c c c c c c c c c c c c c c c c c   | 
     |d  --------|  FA  |-----------------------------------------    | 
     |        |  +------+           |   |    d d d d d d d d d d  |c  | 
     |d       |                     |   |  d ------------------   |   | 
     |        |                     |   |   |         |   |    |d |c  | 
     |d       |                     |   |  d|   dcdcdcdcdcdc +------+ | 
     |        +---------------------+   |   |  c ------------| HA2  | | 
     |d                                 |  d|  d|     |   |  +------+ | 
     |        +---------------------+   +-- |--c|-----+   |     e|    | 
     |d       |                     |      d|  d|         +------|----+ 
     | d d d d d d d d d d d d d d d d d d  |  c|               e|      
      --------------------------------------   d|                |      
              |                     |          c|               e|      
              |  Visited Domain C   |       +-------+       +-------+   
              |                     |       |  CN2  |       |  CN3  |   
              +---------------------+       +-------+       +-------+   
    
   Figure 1: A mobile node with multiple points of attachment in 
             different visited domains. Incoming flows are redirected  
             by the respective Filtering Agents to a different  
             (co-located) care-of address. In addition, mobile node  
             chooses to have its HA2 block flow 'e' . Blocking a flow  
             occurs without notification to the sender. 
    
   Figure 2, illustrates the second model of operation. It shows a 
   mobile node that maintains two points of attachment in visited 
   domains A and B. In addition, the mobile node maintains one active 
   flow from CN1, denoted with 'a'. It can be seen that this flow gets 
     
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   distributed at the HA and variable amounts of the flow are delivered 
   to a different point of attachment. 
    
                                        +-------------+     +-------+   
                                        |   Public    |     |  CN1  |   
                                        |   Network   |     +-------+   
              +---------------------+   |             |          |a     
              |  Visited Domain  A  |   |             |          |      
              |                     |   |             |   +------|a---+ 
      a  a  a |a  a  a  a  a  a  a  a  a| a  a  a  a  a  a| a    |    | 
       ------------------------------------------------------- a |a   | 
     a|       |                     |   |             |   |   |  |    | 
      |       +---------------------+   |             |   |   |a |a   | 
   +------+                             |             |   |  +------+ | 
   |  MN  |   +---------------------+   |             |   |  |  HA  | | 
   +------+   |                     |   |             |   |  +------+ | 
     |a       | a         a         a   |     a       | a |   |       | 
      --------------------------------------------------------        | 
              |                     |   |             |   |    Home   | 
              |  Visited Domain  B  |   |             |   |  Network  | 
              +---------------------+   +-------------+   +-----------+ 
    
   Figure 2: A mobile node with multiple points of attachment in 
             different visited domains. A single incoming flow is  
             distributed by the respective Filtering Agents to a   
             different (co-located) care-of address. 
    
    
4 Backwards compatibility with RFC3344 
    
   A domain that supports Filters for Mobile IPv4 Bindings should also 
   be backwards compatible. In Mobile IPv4, mobile nodes issue 
   registration requests without any Filters and without the æNÆ bit 
   set. Any such registration request would cause a Filtering Agent to 
   act as per [1] and to provide normal Mobile IPv4 services. In 
   addition, it is stated that a Filtering Agent maintaining only Idle 
   Mobility Bindings for a mobile is required to act as per [1] and to 
   ignore the behavior presented in this document. 
    
    
5 Support for Multihoming 
    
   The extension presented in this document are compatible with the 
   multihoming support of Mobile IPv4. In multihoming support a mobile 
   node may use different home addresses in order to distribute 
   incoming flows from different CNs. Filters for Mobile IPv4 Bindings 
   builds on top of that to enable mobile nodes to distribute flows 
   addressed to the same home address from same or different CNs, for 
   one or more home addresses. 
    
    
    
    
     
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6 Associating Filters with Mobility Bindings 
    
   This section gives a detailed description of the steps taken by a 
   mobile node that wishes to associate Filters with its mobility 
   bindings. Furthermore, it is presented how a Filtering Agent reacts 
   to the receipt of a Filtering Request. 
    
6.1 Mobile Node Considerations 
    
   A mobile node that acquires a (co-located) care-of address within a 
   visited domain may issue a Filtering Request with the æNÆ bit set, 
   containing a list of Filters. All included Filters will be 
   associated with the registered (co-located) care-of address at all 
   Filtering Agents encountered on the path to the HA. A mobile node 
   that maintains multiple points of attachment may request for 
   simultaneous mobility bindings by setting the æSÆ bit in its 
   Filtering Requests. 
    
 Filters for Mobile IPv4 Bindings Registration Flag 
    
   The only change to the Registration Request defined in [1] is a flag 
   indicating that the mobile node wishes to receive Filters for Mobile 
   IPv4 Bindings services. The flag is inserted after the flags defined 
   in [5]. 
    
       0                   1                   2                   3 
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |     Type      |S|B|D|M|G|r|T|N|          Lifetime             | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                          Home Address                         | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                           Home Agent                          | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                        Care-of Address                        | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                                                               | 
      +                         Identification                        + 
      |                                                               | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      | Extensions ... 
      +-+-+-+-+-+-+-+- 
    
   The flag is defined as follows: 
    
        N   NOMADv4 Extension. The mobile node wishes to receive  
            Filters for Mobile IPv4 Bindings, services 
    
   Filter declarations and Filter Deletion Extensions are included in a 
   Registration Request after any security extensions. In addition, a 
   Filter Deletion Extension may follow any Filter declarations. 
    
   A Filtering Reply is a Registration Reply containing a Filter Reply 
   Extension for each Filter contained in the respective Filtering 
     
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   Request indicating the Index of the Filter that it refers to along 
   with its result Code. 
    
   For the management of Filters eight scenarios are identified. These 
   are presented in the following sections along with the actions to be 
   undertaken by the mobile node. Following that, the use and different 
   values of the Weight value of the Filter Control Extension are 
   explained. 
    
 Creating a new mobility binding with Filters 
    
   In order to create a new mobility binding with associated Filters 
   the mobile node must issue a Filtering Request including one or more 
   full Filter definitions (Filter Body with Filter Control Extension). 
   Each of the Filters must be allocated a different Index number. 
    
   The destination of the Filtering Request is identified as described 
   in [1] or [5]. If the mobile node already maintains a mobility 
   binding that it wishes to keep then it should set the æSÆ bit in the 
   Filtering Request. 
    
 Replacing a Filter of a mobility binding by Index 
    
   In order for a mobile node to replace an existing Filter it is 
   required to issue a Filtering Request with a full definition of the 
   new Filter. The Filter Control Extension of the Filter must indicate 
   the Index of the Filter to be replaced. 
    
 Adding new Filters to an existing mobility binding 
    
   In order for a mobile node to add new Filters to an existing 
   mobility binding it is required to act as if creating a new mobility 
   binding with Filters. The æSÆ bit of the Filtering Request must be 
   set. It is necessary for the new Filter to adopt an unallocated 
   Index number otherwise it would be replacing the existing Filter 
   with that Index. 
    
 Sharing a Filter between mobility binding 
    
   A mobile node may share a Filter between mobility bindings by 
   issuing a Filtering Request from each respective point of 
   attachment. The first one will contain the full Filter (Filter Body 
   + Filter Control Extension) while all subsequent Filtering Requests 
   will contain only a Filter Control Extension indicating the Index 
   number of the Filter to be shared. 
    
 Renewing a mobility binding with Filters 
    
   Periodically, a mobile node is required to renew its mobility 
   bindings in order to extend their lifetime. Renewing a mobility 
   binding may occur as described in [1] or [5]. Registration Requests 
   with the purpose of renewing Filters and mobility binding are 
   required to set the æNÆ bit and may not include any reference to the 
   Filters associated with the mobility binding. 
     
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 Deleting one or more Filters of a mobility binding 
    
   In order for a mobile node to delete an existing Filter for a 
   mobility binding, it is required to issue a Filtering Request from 
   any (co-located) care-of address. The Filtering Request must include 
   a Filter Deletion Extensions indicating the Index of each Filter to 
   be deleted. 
    
 Deleting all Filters for a mobility binding 
    
   In order for a mobile node to delete all existing Filter for a 
   mobility binding, it is required to issue a Filtering Request from 
   any (co-located) care-of address. The Filtering Request must include 
   a Filter Deletion Extensions with the Index field set to zero. 
    
 Transferring a Filter between mobility bindings 
    
   In order for a mobile node to transfer an existing Filter between 
   two mobility bindings it is required to act as if creating a new 
   mobility binding with Filters and send out a Filtering Request from 
   the point of attachment to which it wants to have the Filter 
   transferred. The Filtering Request must contain the full Filter 
   definition. 
    
 The Weight field of the Filter Control Extension 
    
   The Weight field indicates the relative amount of traffic for which 
   a Filter is applicable. If the Weight field is set to zero then all 
   matching flows will be dropped without notification to their source. 
   For any other value of Weight, matching flows will get forwarded to 
   the point of attachment indicated by the corresponding mobility 
   binding. In the case of shared Filters, packets of matching flows 
   will get distributed between multiple points of attachment with 
   respect to the Weight value of each Filter. 
    
6.2 Filtering Agent Considerations 
    
   This section contains general considerations for Filtering Agents. 
   These are Mobile IPv4 entities that can maintain mobility bindings 
   such as Has, GFAs and RFAs. 
    
 Determining the validity of a Filter Body 
    
   If a Filter Body contains a Protocol Extension with the Protocol 
   field set to the corresponding value for ICMP then the Filter may 
   not include any of the Filter Modules from 5-8 as they refer to 
   sender and receiver port numbers that are not applicable for ICMP.  
    
 Processing Filtering Requests 
    
   A Filtering Request is a Registration Request with the æNÆ bit set 
   that may contain a collection of Filter declarations, Filter Control 
   Extensions or Filter Deletion Extensions.  
     
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   A Filtering Agent is first required to determine the validity of the 
   Filter Body. If the Filter is considered valid then the Filtering 
   Request must be processed like a normal Registration Request, as 
   described in [1]. If the æSÆ bit is set then the Filtering Agent 
   should refrain from deleting any existing mobility bindings for the 
   mobile node. If the æSÆ is not set then all existing mobility 
   bindings must be deleted along with all associated Filters. If the 
   Filter Body is not valid then the Filtering Agent must issue a 
   Filtering Reply with a Filter Control Extension indicating the 
   FilterÆs Index and the error code INVALID SYNTAX (section 7.12). 
    
   For the processing of the Filter Body(s) in a Filtering Request five 
   distinct cases are identified and the actions that a Filtering Agent 
   should undertake are described. 
    
 Filtering Request contains a Filter declaration with a new Index 
    
   A new Filter should be created with the Index and Filter Body 
   contained in the Filtering Request. Newly declared Filters should be 
   associated with the (co-located) care-of address indicated by the 
   Filtering Request. 
    
 Filtering Request containing Filter declarations with allocated Index 
    
   The Filter indicated by the Index contained in the Filtering Request 
   is overwritten and replaced with the Filter Body contained in the 
   Filtering Request. 
    
 Filtering Request containing only Filter Control Extension 
    
   A sole Filter Control Extension indicates the mobile nodes wishes to 
   share the Filter indicated by the Index field of the Filter Control 
   Extension. If the Index refers to an existing Filter, then the 
   Filter should be shared between (co-located) care-of addresses 
   already maintaining an association with the Filter and the (co-
   located) care-of address registered in the Filtering Request. If the 
   Index number indicates a non-existent Filter then the Filtering 
   Request should be denied and a Filtering Reply should be returned to 
   the mobile node containing a Filter Reply Extension with the Index 
   field set to the Index of the non-existent Filter and the Code field 
   set to the NO FILTERS error code. 
    
 Filtering Request containing only Filter Deletion Extension 
    
   A Filtering Agent encountering a Filter Deletion Extension in a 
   Filtering Request should remove the Filter indicated by the Index 
   field in the Filter Deletion Extension. If the indicated Filter does 
   not exist then the Filtering Request should be denied and a 
   Filtering Reply should be returned to the mobile node containing a 
   Filter Reply Extension with the Index field set to the Index of the 
   non-existent Filter and the Code field set to the NO FILTERS error 
   code. 
    
     
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 Filtering Request without any Filter declarations or Extensions 
    
   Filtering Requests that do not contain any Filter declarations or a 
   Filter Deletion Extensions are intended for refreshing the lifetime 
   of a mobility binding and its Filters. If the mobile node does not 
   maintain any Filters for this mobility binding then the Filtering 
   Agent must issue a Filtering Reply including a Filter Reply 
   Extension with the Index set to zero and the Code field set to the 
   NO FILTERS error code indicating that the mobile node does maintain 
   any Filters. 
    
 Applying Filters 
    
   When a Filtering Agent intercepts a packet for a mobile node for 
   which it maintains a mobility binding it is required to identify 
   whether the packet matches any of the Filters associated with the 
   mobility binding. If so, then the packet is forwarded to the 
   respective point of attachment with respect to the Weight value of 
   the Filter. If the Weight value is zero then the flow gets dropped 
   without any notification to its source. If no matching Filter is 
   found then the packet is handled as indicated by the Default Filter. 
   If a flow matches more then one Filter then its packets are 
   distributed between the multiple points of attachment with respect 
   to the Weight value of each Filter. 
    
   When a mobility binding expires or is deregistered by a mobile node 
   then all associated Filters are deleted. Mobility bindings that have 
   been stripped of their Filters are considered to be Idle Mobility 
   Bindings. This means that they remain unused until either allocated 
   a Filter or expire. 
    
6.3 Home Agent Considerations 
    
   When a HA receives a Filtering Request that contains one or more 
   Filter declarations then these Filters must be associated with the 
   registered (co-located) care-of address. Following that, all Filter 
   Control Extensions must be processed. Then the HA is required to 
   issue a Filtering Reply including a Filter Reply Extension for each 
   Filter in the Filtering Request indicating the Index of the Filter 
   and its result Code. 
    
   When a HA receives a Filtering Request without any Filter 
   declarations and Filter Deletion Extensions then it is required to 
   renew the lifetime of the corresponding mobility binding along with 
   its Filters and to issue a Filtering Reply. If the mobility binding 
   has no associated Filters then the HA must issue a Filtering Reply 
   including a Filter Reply Extension with the Index set to zero and 
   the Code field set to the NO FILTERS error code indicating that the 
   mobile node does maintain any Filters. 
    
   For each Filter in a Filtering Request, a Filtering Agent must 
   include a Filter Reply Extension indicating its Index and its result 
   Code. If authentication of the Filtering Request fails then none of 
   the Filters must be applied. 
     
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 Filters for Mobile IPv4 Bindings Flag 
    
   The only change to the Mobility Agent Advertisement Extension 
   defined in [1] is a flag indicating that the HA supports Filters for 
   Mobile IPv4 Bindings. The flag is inserted after the flags defined 
   in [5]. 
    
      0                   1                   2                   3 
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |     Type      |    Length     |        Sequence Number        | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |           Lifetime            |R|B|H|F|M|G|V|T|S|I|N|reserved | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |     zero or more (co-located) care-of addresses               | 
      |                              ...                              | 
    
   The flag is defined as follows: 
    
        N   NOMADv4 Extension. This domain supports Filters for Mobile  
            IPv4 Bindings as specified in this document. 
    
    
7 NOMADv4 Extensions to RFC3344 Registration Messages 
    
   In this section the new Mobile IPv4 registration extensions required 
   for the support of Filters for Mobile IPv4 bindings are specified. 
    
   In NOMADv4, twelve types of extensions are defined. To form a valid 
   Filter, at least one of the extensions 1 to 9, termed as Filter 
   Modules, must be included. Extension 10 must appear once in every 
   Filter following all Filter Modules. Extension 11 may appear only 
   once in a Filtering Request after any Filter declarations. Finally, 
   extension 12 may appear several times within a Filtering Reply. 
    
   Filter Modules of the same type may not appear in a Filter more than 
   once. However, a Filter Module may include one or more predicates. 
   There is an OR relationship between Filter Module predicates. That 
   is, in order for a flow to match a Filter Module it is required to 
   qualify for any of its predicates. In addition, there is an AND 
   relationship between Filter Modules of a Filter. As such, in order 
   for a flow to match a Filter it is required to qualify for all its 
   Filter Modules.  
    
   All extensions defined in this document follow the short extension 
   format defined in [1]. In Filter Modules, the leftmost bit of the 
   Sub-Type field is used to determine whether the rules included in 
   the Filter Module are positive or negative. In the first case a flow 
   is required to match exactly the predicates included in the Filter 
   Module while in the second, the inverted (NOT) rule. 
    
   1. Behavior Aggregate Filters Extension (BAF) 
      Identifies data packets dependent of the content of the DSCP  
     
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      field. 
    
   2. Protocol Extension 
      Specifies one or more protocols to be filtered. 
    
   3. Source Address Extension 
      Specifies one or more source adresses to be filtered. 
    
   4. Source Network Extension 
      Specifies one or more source networks (i.e. a interval of 
      IP addresses) to be filtered. 
    
   5. Source Port Extension 
      Specifies one or more source ports to be filtered. 
    
   6. Source Port Range Extension 
      Specifies one or more ranges of source ports to be filtered. 
    
   7. Destination Port Extension 
      Specifies one or more destination ports to be filtered. 
    
   8. Destination Port Range Extension 
      Specifies one or more ranges of destination ports to be filtered. 
    
   9. Free-Form Extension 
      It allows for the definition of complex Filters based on the 
      value of an area anywhere within a packet. The mobile node 
      is required to provide the packet offset, the qualifying 
      value as well as a mask. 
    
   10. Filter Control Extension 
      It contains a FilterÆs unique identifier, called the Index along  
      with the FilterÆs Weight factor. 
    
   11. Filter Deletion Extension 
      It contains a list of Filter Index numbers to be deleted. 
    
7.1 Behavior Aggregate Filters (BAF) Extension 
    
      0                   1                   2                   3 
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |     Type      |    Length     |I|  Sub-Type   |    DSCP   |RSV| 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
         Type      The type, which describes a collection of extensions 
                   having a common data type. (To Be Defined). 
    
         Length    (N), where N is the number of DSCP entries 
    
         Sub-Type  0 for given predicates, 128 for inverted predicates. 
    
         I (INVERT)A single bit at the beginning of the Sub-Type field  
                   used to invert predicates of Filter Module. Due to  
     
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                   this bit two different Sub-Type values are given. 
    
         DSCP      Differentiated Services CodePoint 
    
   In Differentiated Services (DS) [7] the DS header field is defined 
   as a replacement for the IPv4 TOS [6] octets. Six bits of the DS 
   field are used as a codepoint (DSCP) to select the per-hop-behavior 
   that a packet receives at each node. For the purposes of NOMADv4 the 
   DSCP along with other header fields is used to construct Filters 
   that identify a specific flow or groups of them. 
    
   This Filter Module does not in any way alter or affect the DSCP 
   value of intercepted packets. 
    
7.2 Protocol Extension 
    
      0                   1                   2                   3 
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |     Type      |    Length     |I|  Sub-Type   |   Protocol    | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
         Type      The type, which describes a collection of extensions 
                   having a common data type. (To Be Defined). 
    
         Length    (N), where N is the number of Protocol fields 
    
         Sub-Type  1 for given predicates, 129 for inverted predicates 
    
         I (INVERT)A single bit at the beginning of the Sub-Type  
                   field used to invert predicates of Filter Module.  
                   Due to this bit two different Sub-Type values are  
                   given. 
    
         Protocol  Identifies the next level protocol used in the data 
                   portion of the internet datagram. The values for  
                   various protocols are specified in [4]. 
    
7.3 Source Address Extension 
    
   The Source Address Extension is defined for IPv4 and IPv6. 
    
      0                   1                   2                   3 
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1   
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |     Type      |I|  Sub-Type   |             Length            | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |                       Source IP Address                       | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
         Type      The type, which describes a collection of extensions 
                   having a common data type. (To Be Defined). 
    
         Length    (4*N), where N is the number of source IP address  
     
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                   Fields. 
    
         Sub-Type  2 for given predicates, 130 for inverted predicates. 
    
         I (INVERT)A single bit at the beginning of the Sub-Type field  
                   used to invert predicates of Filter Module. Due to  
                   this bit two different Sub-Type values are given. 
    
   Source IP Address 
                   Identifies the source IP address contained in the IP  
                   header of an incoming flow. 
    
7.4 Source Network Extension 
    
      0                   1                   2                   3 
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |     Type      |I|  Sub-Type   |             Length            | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |                       Source IP Address                       | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |                     Source IP Address Mask                    | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
         Type      The type, which describes a collection of extensions 
                   having a common data type. (To Be Defined). 
    
         Sub-Type  3 for given predicates, 131 for inverted predicates. 
    
         I (INVERT)A single bit at the beginning of the Sub-Type  
                   field used to invert predicates of Filter Module.  
                   Due to this bit two different Sub-Type values are  
                   given. 
    
         Length   (8*N), where N is the number of pairs of a 
                   source IP address and a corresponding source 
                   IP address mask entry. 
    
   Source IP Address 
                   Identifies the base network IP address of a range of  
                   source IP addresses. 
    
   Source IP Address Mask 
                   Based on the source IP address field, identifies the  
                   range of source IP addresses. 
    
    
    
    
    
    
    
    
    
     
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7.5 Source Port Extension 
    
      0                   1                   2                   3 
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |     Type      |I|  Sub-Type   |             Length            | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |          Source Port          | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
         Type      The type, which describes a collection of extensions 
                   having a common data type. (To Be Defined). 
    
         Sub-Type  4 for given predicates, 132 for inverted predicates. 
    
         I (INVERT)A single bit at the beginning of the Sub-Type  
                   field used to invert predicates of Filter Module.  
                   Due to this bit two different Sub-Type values are  
                   given. 
    
         Length    (2*N), where N is the number of port entries. 
    
         Source Port 
                   Identifies the source port number contained in the 
                   IP header of an incoming flow. 
    
7.6 Source Port Range Extension 
    
      0                   1                   2                   3 
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |     Type      |I|  Sub-Type   |             Length            | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |        Source Port Min        |        Source Port Max        | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
         Type      The type, which describes a collection of extensions 
                   having a common data type. (To Be Defined). 
    
         Sub-Type  5 for given predicates, 133 for inverted predicates. 
    
         I         Invert. A single bit at the beginning of the Sub-
   Type  
                   field used to invert predicates of Filter Module.  
                   Due to this bit two different Sub-Type values are  
                   given. 
    
         Length    (4*N), where N is the number of port range entries. 
    
         Source Port Number Min 
                   Defines the start point of a range of source port 
                   numbers. 
    
         Source Port Number Max 
     
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                  Defines the end point of a range of source port  
                  Numbers. 
    
7.7 Destination Port Extension 
    
      0                   1                   2                   3 
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |     Type      |I|  Sub-Type   |             Length            | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |        Destination Port       | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
         Type      The type, which describes a collection of extensions 
                   having a common data type. (To Be Defined). 
    
         Sub-Type  6 for given predicates, 133 for inverted predicates. 
    
         I (INVERT)A single bit at the beginning of the Sub-Type  
                   field used to invert predicates of Filter Module.  
                   Due to this bit two different Sub-Type values are  
                   given. 
    
         Length    (2*N), where N is the number of port entries 
    
         Destination Port 
                   Identifies the destination port number contained in  
                   the IP header of an incoming flow. 
    
7.8 Destination Port Range Extension 
    
      0                   1                   2                   3 
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |     Type      |I|  Sub-Type   |             Length            | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |      Destination Port Min     |      Destination Port Max     | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
         Type      The type, which describes a collection of extensions 
                   having a common data type. (To Be Defined). 
    
         Sub-Type  7 for given predicates, 134 for inverted predicates. 
    
         I (INVERT)A single bit at the beginning of the Sub-Type  
                   field used to invert predicates of Filter Module.  
                   Due to this bit two different Sub-Type values are  
                   given. 
    
         Length    (4*N), where N is the number of port range entries 
    
         Destination Port Number Min 
                   Defines the start point of a range of destination  
                   port numbers 
     
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         Destination Port Number Max 
                   Defines the end point of a range of destination port 
                   numbers 
    
7.9 Free-Form Extension 
    
      0                   1                   2                   3 
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |     Type      |I|  Sub-Type   |             Length            | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |             Offset            |              Value              
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
                                   .... 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |                              Mask                               
                                   .... 
    
         Type      The type, which describes a collection of extensions 
                   having a common data type. (To Be Defined). 
    
         Sub-Type  7 for given predicates, 134 for inverted predicates. 
    
         I (INVERT)A single bit at the beginning of the Sub-Type  
                   field used to invert predicates of Filter Module.  
                   Due to this bit two different Sub-Type values are  
                   given. 
    
         Length    Is variable, depends on the length of Value and  
                   Mask. 
    
         Offset    Indicates a location within a packet to be filtered 
                   in bytes. 
    
   The area indicated by the offset and for a length equivalent to that 
   of Mask is compared against Mask with the bitwise operator AND. The 
   result of this operation is compared against Value. A match would 
   indicate that the packet qualifies the filter. 
    
   Value and Mask fields MUST have exactly the same size. However, this 
   size may vary with every free-form filter. For the sizes of Value 
   and Mask the following condition holds: 
    
   Value = Mask = (Length - 2) / 2 
    
    
    
    
    
    
    
    
     
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7.10 Filter Control Extension 
    
      0                   1                   2                   3 
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |     Type      |    Sub-Type   |    Length     |     Index     | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |    Weight     | 
     +-+-+-+-+-+-+-+-+ 
    
         Type      The type, which describes a collection of extensions 
                   having a common data type. (To Be Defined). 
    
         Sub-Type  125. 
    
         Length    2. 
    
         Index     FilterÆs index number 
    
         Weight    Relative amount of traffic for which forwarding  
                   Filter is applicable 
    
7.11 Filter Deletion Extension 
    
      0                   1                   2       
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |     Type      |    Sub-Type   |     Index     | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
         Type      The type, which describes a collection of extensions 
                   having a common data type. (To Be Defined). 
    
         Sub-Type  126 
    
         Length    N, where N is the number of Index entries 
    
         Index     A FilterÆs index number 
    
7.12 Filter Reply Extension 
    
      0                   1                   2                   3 
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |     Type      |    Sub-Type   |    Length     |      Code     | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |     Index     | 
     +-+-+-+-+-+-+-+-+ 
    
         Type      The type, which describes a collection of extensions 
                   having a common data type. (To Be Defined). 
    
         Sub-Type  127. 
    
     
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         Length    2. 
    
         Index     A FilterÆs index number. 
    
 Code Values for Filter Reply Extension 
    
   In this section the values to use within the Code field of the 
   Filter Control Extension are defined: 
    
   Successful Filtering Request Codes: 
    
         Code Name                Value   Section of Document 
         ----------------------   -----   ------------------- 
         REQUEST ACCEPTED         TBD 
    
   Failed Filtering Request Codes: 
    
         Error Name               Value   Section of Document 
         ----------------------   -----   ------------------- 
         NO FILTERS               TBD 
         TOO MANY FILTERS         TBD 
         INVALID FILTER SYNTAX    TBD 
         UNKNOWN FILTER           TBD 
         CAN NOT DROP MIP SIG     TBD 
    
   The Error Code CAN NOT DROP MIP SIG is used when the mobile node 
   issues a Filtering Request requesting the drop of flows 
   corresponding to Mobile IPv4 signaling such as Agent Advertisements 
   or Registration Requests and Replies. 
    
    
8. Security Considerations 
    
   This draft is based on the security considerations provided in [1] 
   for mobile node registration and as such does not specifically 
   address any security concerns. 
    
9 Intellectual Property Considerations 
    
   This proposal is in full conformity with [9]. 
    
   Siemens may have patent rights on technology described in this 
   document which employees of Siemens contribute for use in IETF 
   standard discussions. In relation to any IETF standard incorporating 
   any such technology, Siemens hereby agrees to license on fair, 
   reasonable and non-discriminatory terms, based on reciprocity, any 
   patent claims it owns covering such technology, to the extent such 
   technology is essential to comply with such standard. 
    
    
    
    
    
    
     
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References 
    
[1]     C. Perkins. IP Mobility Support. RFC (Proposed Standard) 3344,  
        IETF, August 2002. 
[2]     S. Bradner. Key words for use in RFCs to Indicate Requirement  
        Levels. RFC 2119, IETF, March 1997. 
[3]     C. Perkins and D. Johnson. Route Optimization in Mobile IP. 
        (work in progress). draft-ietf-mobileip-optim-11.txt, 
        IETF, September 2001. (expired; not updated) 
[4]     J. Reynolds and J. Postel. Assigned Numbers. Request for 
        Comments 1700, STD 2, IETF, October 1994. 
[5]     E. Gustafsson, A. Jonsson and C. Perkins. Mobile IP Regional  
        Registration. (work in progress). 
        draft-ietf-mobileip-reg-tunnel-07.txt, IETF, October 2002. 
[6]     Postel, J. Internet Protocol. STD 5, RFC 791, IETF, 
        September 1981. 
[7]     K. Nichols, S. Blake, F. Baker, and D. Black. Definition of 
        the Differentiated Services Field (DS Field) in the IPv4 and 
        IPv6 Headers. RFC 2474, IETF, December 1998. 
[8]     S. Deering and R. Hinden, Internet Protocol, Version 6 (IPv6)  
        Specification. RFC 2460, IETF, December 1998. 
[9]     S. Brander. The Internet Standards Process -- Revision 3. RFC  
        2026, IETF, October 1996 
 
 
A. Changes from Previous Versions 
    
   The following updates and changes were made in this version of the 
   Filters for Mobile IPv4 Bindings draft, compared to earlier 
   versions. 
    
A.1. Updates from version 02 
    
   Version 3 is almost a complete rewrite of version 2, based on 
   experience acquired from the implementation of version 2. 
    
   Renamed Binding Agents to Filter Agents and Binding Requests & 
   Replies to Filtering Requests & Replies. 
    
   Defined in section 3.2 Model of operation that a mobile node may not 
   maintain more then one points of attachment in a single subnetwork. 
   Should the mobile node acquire one point of attachment in the home 
   network then all other must be given up. 
    
   Defined in section 3.1 Protocol Description and in the beginning of 
   section 5 NOMADv4 Extensions to RFC3344 Registration Messages the 
   structure of a Filter and the relation between Filter Module 
   predicates, Filter Modules and Filters. In addition, the Filter 
   Control Extension was renamed as Filter Target Extension while a new 
   extension by the name Filter Control Extension was defined. Removed 
     
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   Action field from Filter Target Extension and increased Target and 
   Index fields to occupy 8 bits. 
    
   Removed P and A bits from Free Form Filter. 
    
   Added section 4 Backwards compatibility with RFC3344 
    
   Extended section on Mobile Node Considerations and Filtering Agent 
   Considerations in section 5 Associating Filters with Mobility 
   Bindings. Described specific actions undertaken by mobile node. 
    
   Renamed Default Binding to Default Filter and redefined it. Now 
   Fitlerless mobility bindings may not be Default Bindings. 
    
   Clarified that Index number denotes priority. 0 is lowest priority. 
   Index 0 is reserved for Default Filter. 
    
   Introduced the Filter Reply Extension for the relay of success and 
   error codes from Filtering Agents to mobile nodes. Defined success 
   and error codes. 
    
   Included INVERT flag in Filter Modules. 
    
   Introduced destination port and destination port range Filter 
   Modules. 
    
   Remove all reference to Filters for Mobile IPv6 bindings as this be 
   the purpose of a separate Internet draft. 
    
A.2. Updates from version 03 
    
   Removed all reference to Mobile IPv4 routing optimization. 
    
   Merged the Filter Target and Filter Control Extensions. 
    
   Introduced the æNÆ bit in the Registration Request and Reply 
   messages. 
    
   Removed the Target field from the Filter Control Extension 
    
   Introduced the Weight field in the Filter Control Extension. 
    
   Introduced the Filter Deletion Extension 
    
   Edited the sections for mobile node and filtering agent 
   considerations 
    
   Added a section on determining the validity of Filter Bodies. 
    
A.3. Updates from version 04 
    
   Introduced shared Filters based on the Index field. 
    
   Introduced a section for compatibility issues with multihomming 
     
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Authors' Addresses 
    
   Niko A. Fikouras 
   Department of Communication Networks (ComNets) 
   Center for Information and Communication Technology (ikom) 
   University of Bremen         Phone:  +49-421-218-3339 
   D-28219 Bremen, Germany      Email:  niko@comnets.uni-bremen.de 
    
   Asanga Udugama 
   Department of Communication Networks (ComNets) 
   Center for Information and Communication Technology (ikom) 
   University of Bremen         Phone:  +49-421-218-8665 
   D-28219 Bremen, Germany      Email:  adu@comnets.uni-bremen.de 
    
   Koojana Kuladinithi 
   Department of Communication Networks (ComNets) 
   Center for Information and Communication Technology (ikom) 
   University of Bremen         Phone:  +49-421-218-8264 
   D-28219 Bremen, Germany      Email:  koo@comnets.uni-bremen.de 
    
   Carmelita Goerg 
   Department of Communication Networks (ComNets) 
   Center for Information and Communication Technology (ikom) 
   University of Bremen         Phone:  +49-421-218-2277 
   28219, Bremen, Germany       Email:  cg@comnets.uni-bremen.de 
    
   Wolfgang Zirwas 
   Siemens AG 
   ICM N MR-ST 8 
   Werner-von-Siemens Ring 20 
   D-85630 Grasbrunn            Phone:  +49-89-722-34369 
   Germany                      Email:  wolfgang.zirwas@icn.siemens.de 
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
     
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